Tuning thermal conductivity in homoepitaxial SrTiO3 films via defects

We demonstrate the ability to tune the thermal conductivity of homoepitaxial SrTiO3 films deposited by reactive molecular-beam epitaxy by varying growth temperature, oxidation environment, and cation stoichiometry. Both point defects and planar defects decrease the longitudinal thermal conductivity (k33), with the greatest decrease in films of the same composition observed for films containing planar defects oriented perpendicular to the direction of heat flow. The longitudinal thermal conductivity can be modified by as much as 80%—from 11.5 W m−1K−1 for stoichiometric homoepitaxial SrTiO3 to 2 W m−1K−1 for strontium-rich homoepitaxial Sr1+δTiOx films—by incorporating (SrO)2 Ruddlesden-Popper planar defects.